How is the Internet changing the way I think? My fingers have become part of my brain. What will come of this? It's far too early to say.

Once upon a time, knowledge consisted of what you knew yourself and what you heard â€” literally, with your ears â€” from others. If you were asked a question in those days you thought of what you had seen and heard and done yourself and what others had said to you. I'm rereading Thucydides this winter and watching the way everything depended on who you knew and where the messengers came from and whether they were delayed en route, walking from one end of Greece to another. Thucydides was literate, but his world hadn't absorbed that new technology yet.

With the invention of writing, the eyes took on a new role. Knowledge wasn't all in memory, but was found in present, visual stimuli: the written word in one form or another. We have built a might culture based on all the things that humankind can produce and the eye can study. What we could read in the traditional library of 25 years ago was orders of magnitude richer and more diverse than the most that any person could ever see, hear, or be told of in one lifetime. The modern correlative to Thucydides would be Churchill's history of World War II and the abundance of written documents he shows himself dependent on at every stage of the war. But imagine Churchill or Hitler with Internet-like access to information!

Now we change again. It's less than twenty years since the living presence of networked information has become part of our thinking machinery. What it will mean to us that vastly more people have nearly instantaneous access to vastly greater quantities of information cannot be said with confidence. In principle, it means a democratization of innovation and of debate. In practice, it also means a world in which many have already proven that they can ignore what they do not wish to think about, select what they wish to quote, and produce a public discourse demonstrably poorer than what we might have known in the past.

But just for myself, just for now, it's my fingers I notice. Ask me a good question today, and I find that I begin fiddling. If I am away from my desk, I pull out my Blackberry so quickly and instinctively that you probably think I'm ignoring your question and starting to read my e-mail or play Brickbreaker â€” and sometimes I am! But when I'm not â€” that is, when you've asked a really interesting question, it's a physical reaction, a gut feeling that I need to start manipulating (the Latin root for 'hand', *manus*, is in that word) the information at my fingertips, in order to find the data that will support a good answer. At my desktop, it's the same pattern: the sign of thinking is that I reach for the mouse and start "shaking it loose" â€” the circular pattern on the mouse pad that lets me see where the mouse arrow is, make sure the right browser is open, get a search window handy. My eyes and hands have already learned to work together in new ways with my brain in a process of clicking, typing a couple of words, clicking, scanning, clicking again that really is a new way of thinking for me.

That finger work is unconscious. It just starts to happen. But it's the way I can now tell thinking has begun as I begin working my way through an information world more tactile than ever before. Will we next have three-dimensional virtual spaces in which I gesture, touch, and run my fingers over the data? I don't know: nobody can. But we're off on a new and great adventure whose costs and benefits we will only slowly come to appreciate.

What all this means is that we are in a different space now, one that is largely unfamiliar to us even when we think we are using familiar tools (like a "newspaper" that has never been printed or an "encyclopedia" vastly larger than any shelf of buckram volumes), and one that has begun life by going through rapid changes that only hint at what is to come. I'm not going to prophesy where that goes, but I'll sit here a while longer, watching the ways I really have come to "let my fingers do the walking", wondering where they will lead.